Vortex phenomena in sidewall aneurysm hemodynamics: experiment and numerical simulation.

We carry out high-resolution laboratory experiments and numerical simulations to investigate the dynamics of unsteady vortex formation across the neck of an anatomic in vitro model of an intracranial aneurysm. A transparent acrylic replica of the aneurysm is manufactured and attached to a pulse duplicator system in the laboratory. Time-resolved three-dimensional three-component velocity measurements are obtained inside the aneurysm sac under physiologic pulsatile conditions.

Mechanical stress: an independent determinant of early bioprosthetic calcification in humans.

Background: Mechanical stress is one of the contributing factors for bioprosthetic calcification. A HeartMate XVE (Thoratec, CA) left ventricular assist device (LVAD) has two identical porcine valves, one for inflow and the other for outflow. The inflow valve endures a higher closing pressure than the outflow valve; thus, an implanted LVAD offers an ideal human model to study the independent effect of stress on calcification.